1. Field of the Invention
This invention relates to pharmaceutical, ophthalmic or cosmetic compositions containing quaternary ammonium compounds, more preferably to ophthalmic emulsions being useful for eye care or for the treatment of eye conditions. This invention also relates to compositions including at least one quaternary ammonium compound as a cationic agent.
2. Description of the Related Art
Quaternary ammonium compounds are organic compounds usually used as antiseptic or antimicrobial agents. For example, benzalkonium chloride is a nitrogenous cationic surface-acting agent belonging to the quaternary ammonium group. Benzalkonium chloride is generally defined as a mixtures of compounds of general formula C6H5CH2N(CH3)2RCl, where R is a C12-C24 alkyl group.
Benzalkonium chloride, as usually provided by the manufacturers wanting to comply with the European and/or American Pharmacopeia, is a mixture of n-alkyl dimethyl benzyl ammonium chlorides of various alkyl chain lengths. For example, FeF Chemicals A/S (Denmark) supplies, under reference 8100301U (BAK USP/NF), a mixture of three alkyl dimethyl benzyl ammonium chlorides including: (1) 60-70% of C12-alkyl dimethyl benzyl ammonium chloride (2) 30-40% of C14-alkyl dimethyl benzyl ammonium chloride, and less than 5% of C16-alkyl dimethyl benzyl ammonium chloride
Benzalkonium chloride, as a mixture of alkyl dimethyl benzyl ammonium having various alkyl chain lengths is used as preservative agent in topical ophthalmic products. Benzalkonium chloride also has cationic agent properties, and was used as cationic agents for emulsions, especially ophthalmic emulsions.
When mixtures of benzalkonium chlorides having various alkyl chain lengths are used in emulsions, they may act both as preservative agents and cationic agents. However, the toxicity of these materials renders their use problematic.